1. Field of the Invention
The present invention relates to a medium fixing method and medium support apparatus and, more particularly, to a medium fixing method and medium support apparatus suitable for an apparatus, for positioning/fixing an information recording/reproducing medium such as a hard disk, optical disk, or optical card or a medium such as a semiconductor wafer to a shaft and rotating the medium at a high speed while reducing the axis deflection amount.
2. Related Background Art
FIG. 7 is a sectional view of the main part of a conventional medium support apparatus. In the medium support apparatus shown in FIG. 7, when a plurality of magnetic disks as mediums 101 are to be stacked on a shaft 103, ring-like spacers 102 are inserted between the mediums 101, and the mediums 101 are fixed with a clamper 104 to keep them parallel. This arrangement mainly aims at suppressing axis deflection of the mediums 101 when the shaft 103 rotates. In addition, the mediums 101 are alternately pressed against the shaft 103 to be fixed while the gaps between holes 101a of the respective mediums and the shaft 103 are distributed to an arbitrary virtual axis, thereby suppressing dynamic weight balance disturbance caused by slight gaps between inner circumferential surfaces 101b of the mediums 101 and the shaft 103.
Recently, information recording apparatus have been required to record large volumes of information, and there are increasing tendencies to increase the recording density and rotational speed of recording mediums in the apparatuses. In order to attain high recording density and high rotational speed, a reduction in track pitch and strict track pitch error control are required. To meet these requirements, any eccentricity between each medium 101 and a driving shaft 7 must be suppressed as well as synchronous and asynchronous vibrations of the driving shaft 7. As compared with the required track pitch precision, the standard diameter tolerance of the hole 101a in the central portion of the medium 101 is very large. The eccentricity caused between the driving shaft 7 or shaft 103 and the medium 101 makes it difficult to improve the track pitch precision.
In addition, in rotating the medium 101, the dynamic weight balance disturbance in the medium support apparatus including the mediums 101 produces vibrations. At a high rotational speed, this disturbance vibrates not only the driving shaft 7 but also the magnetic recording converter such as a magnetic head through the base on which the motor (not shown) is fixed, interfering with high-precision positioning of these components. Furthermore, stacking many mediums 101 makes it difficult to correct the eccentricity between each medium and the shaft 103, and increases the dynamic weight balance disturbance in the medium support apparatus.
As described above, the conventional medium support apparatus mainly aims at suppressing surface deflection of the mediums 101 in the horizontal direction. However, no function of correcting the eccentricity of each medium and the dynamic weight balance of the medium support apparatus is added to the apparatus. For this reason, the mediums 101 are alternately pressed against the shaft 103, and the gaps between the inner circumferential surfaces 101b of the respective mediums 101 and the shaft 103 are distributed to an arbitrary virtual axis, thus suppressing the dynamic weight balance disturbance. This, however, maximizes the gaps between the respective mediums 101 and the shaft 103, and the eccentricity value becomes xc2xd times the tolerance size of the hole 101a in the central portion of each medium. Under these circumstances, demands have arisen for a medium support apparatus capable of positioning/fixing mediums while keeping dynamic weight balance by correcting the eccentricity of each medium.
It is an object of the present invention to provide a medium fixing method and medium support apparatus, which can reduce the axis deflection amounts of mediums such as magnetic disks with respect to a driving shaft when one or a plurality of mediums are positioned/fixed on a shaft, and can accurately rotate/drive the mediums at high speed.
According to one aspect of the present invention, there is provided a medium fixing method of fixing one or a plurality of mediums on a shaft while the one or a plurality of mediums each having a circular opening portion in a substantially center are stacked and the shaft is inserted into the opening portions, comprising fixing the mediums to the shaft while guiding the mediums into which the shaft is inserted with a fluid.
According to further aspect of the present invention, there is provided a medium fixing method of fixing one or a plurality of mediums on a shaft while the one or the plurality of mediums each having a circular opening portion in a substantially center are stacked and the shaft is inserted into the opening portions, comprising fixing the mediums to the shaft while performing position adjustment between the shaft and the mediums by forming a fluid film between a side surface portion of the shaft and inner circumferential surfaces of the opening portions of the mediums.
According to further aspect of the present invention, there is provided a medium fixing method of fixing one or a plurality of mediums on a shaft while the one or plurality of mediums each having a circular opening portion in a substantially center are stacked and the shaft is inserted into the opening portions, comprising fixing the mediums to the shaft while performing position adjustment between the mediums and the shaft by preparing a guide around the mediums and forming a fluid film between an inner surface portion of the guide and outer circumferential surfaces of the mediums.
According to further aspect of the present invention, the foregoing method further comprises inserting the shaft into the opening portions while the mediums are stacked with spacers being inserted therebetween.
According to further aspect of the present invention, there is provided a medium support apparatus comprising a function of stacking one or a plurality of mediums each having a circular opening portion in a substantially center, inserting a shaft into the opening portions of the mediums, inserting a porous material between a side surface portion of the shaft and inner circumferential surfaces of the opening portions of the mediums, and adjusting gaps between the inner circumferential surfaces of the opening portions of the mediums and the shaft by forming a fluid film between a side surface portion of the shaft and the inner circumferential surfaces of the opening portions of the mediums, thereby positioning the mediums.
According to further aspect of the present invention, there is provided a medium support apparatus comprising a function of stacking one or a plurality of mediums each having a circular opening portion in a substantially center, inserting a shaft into the opening portions of the mediums, fixing the mediums to the shaft, disposing a guide having a cylindrical porous material having an opening with a diameter substantially equal to an outer diameter of the mediums, and adjusting gaps between outer circumferential surfaces of the mediums and an inner surface of the guide by forming a fluid film between the inner surface of the guide and the outer circumferential surfaces of the mediums, thereby positioning the mediums.
According to further aspect of the invention, in the foregoing apparatus, the plurality of mediums are stacked with ring-like spacers being inserted between the respective mediums.
According to further aspect of the present invention, the foregoing apparatus further comprises fixing means for fixing the mediums to the shaft.